18.md

Perl 中的unless-else语句

原文： https://beginnersbook.com/2017/02/unless-else-statement-in-perl/

类似于unless语句，Perl 中的unless-else语句与if-else语句相反。在except-else中，如果条件为false，执行内部语句，如果条件为true，则执行else内的语句。

unless(condition) {
   #These statements would execute
   #if the condition is false.
   statement(s);
}
else {
   #These statements would execute
   #if the condition is true.
   statement(s);
}

例

#!/usr/local/bin/perl

printf "Enter any number:";
$num = <STDIN>;
unless($num>=100) {
   #This print statement would execute,
   #if the given condition is false
   printf "num is less than 100\n";
}
else {
   #This print statement would execute,
   #if the given condition is true
   printf "number is greater than or equal to 100\n";
}

输出：

Enter any number:100
number is greater than or equal to 100